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Colorado Tick Fever Clinical Presentation

  • Author: Cassis Thomassin, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
 
Updated: Jan 21, 2016
 

History

Colorado tick fever presents as a nonspecific febrile illness with few historical clues (other than the epidemiology) to suggest the disease.[7] Consider the diagnosis in any patient with a febrile illness who lives in or who recently visited an endemic area. Most patients are males aged 15-45 years who present between April and August. Findings may include a history of tick bite, fever, and flulike symptoms.

Most patients have a history of exposure to ticks, but only about half recall tick attachment. Therefore, although a history of a tick bite is an important clue, its absence does not exclude the diagnosis. The patient may also have a history of participation in activities that put him or her at risk for a tick bite.

Fever is present in nearly all cases. A characteristic fever pattern noted in about one half of cases of Colorado tick fever is so-called “saddleback fever”, which strongly suggests the diagnosis. Patients with this pattern have a fever for 2-3 days, followed by an afebrile period of similar duration and then by another 2-3 days of fever.

Common flulike symptoms include the following:

  • Headache
  • Myalgias
  • Arthralgias
  • Fatigue

In addition, a nonspecific evanescent rash may be present (5-15% of cases), sometimes with a palatal enanthema. Stiff neck, retroorbital pain, photophobia[1] , nausea and vomiting, abdominal pain, diarrhea, and sore throat all have been reported in a minority of patients. In one series, patients with suspected Colorado tick fever and symptoms of abdominal pain, rash, or sore throat were less likely to have Colorado tick fever on the basis of serologic diagnoses.

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Physical Examination

Physical examination is not particularly helpful for diagnosing Colorado tick fever. Findings may include rash and nuchal rigidity.

In 5-15% of patients, a macular, maculopapular, and petechial rash is present. Occasionally, a small, red, painless papule (presumably at the bite site) is present. The distribution is often truncal, in contrast to the more acral rash in Rocky Mountain spotted fever. The rash tends to be short lived, which is another difference compared with Rocky Mountain spotted fever. Petechiae occur in rare cases and may be complicated by thrombocytopenia. A palatal enanthema is sometimes present.

Nuchal rigidity is found in 15-20% of cases. Splenomegaly may occur. Some patients have altered sensorium or even coma.

Complications of Colorado tick fever are unusual and rare. Cases with neurologic disease, including meningitis and meningoencephalitis, are reported, especially in children.[6]

 

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Contributor Information and Disclosures
Author

Cassis Thomassin, MD Clinical Assistant Instructor, Resident Physician, Department of Emergency Medicine, SUNY Downstate Medical Center

Cassis Thomassin, MD is a member of the following medical societies: American College of Emergency Physicians, Emergency Medicine Residents' Association

Disclosure: Nothing to disclose.

Coauthor(s)

Ninfa Mehta, MD, MPH Clinical Assistant Professor, Ultrasound Fellowship Director, Department of Emergency Medicine, Kings County Hospital, State University of New York Downstate Medical Center

Ninfa Mehta, MD, MPH is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Medical Student Association/Foundation, Society for Academic Emergency Medicine, American Association of Physicians of Indian Origin

Disclosure: Nothing to disclose.

Chief Editor

Jeter (Jay) Pritchard Taylor, III, MD Assistant Professor, Department of Surgery, University of South Carolina School of Medicine; Attending Physician, Clinical Instructor, Compliance Officer, Department of Emergency Medicine, Palmetto Richland Hospital

Jeter (Jay) Pritchard Taylor, III, MD is a member of the following medical societies: American Academy of Emergency Medicine, South Carolina Medical Association, Columbia Medical Society, South Carolina College of Emergency Physicians, American College of Emergency Physicians, American Medical Association, Society for Academic Emergency Medicine

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Chief Editor for Medscape.

Additional Contributors

Massoud G Kazzi, MD Fellow, Department of Critical Care Medicine, Montefiore Medical Center

Disclosure: Nothing to disclose.

Acknowledgements

Dan Danzl, MD Chair, Department of Emergency Medicine, Professor, University of Louisville Hospital

Dan Danzl, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Kentucky Medical Association, Society for Academic Emergency Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Jonathan A Edlow, MD Associate Professor of Medicine, Department of Emergency Medicine, Harvard Medical School; Vice Chairman, Department of Emergency Medicine, Beth Israel Deaconess Medical Center

Jonathan A Edlow, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Jon Mark Hirshon, MD, MPH Associate Professor, Department of Emergency Medicine, University of Maryland School of Medicine

Jon Mark Hirshon, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Public Health Association, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Reference Salary Employment

References
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  11. Lindquist L, Vapalahti O. Tick-borne encephalitis. Lancet. 2008 May 31. 371 (9627):1861-71. [Medline].

  12. Centers for Disease Control and Prevention (CDC). Tick-borne encephalitis among U.S. travelers to Europe and Asia - 2000-2009. MMWR Morb Mortal Wkly Rep. 2010 Mar 26. 59 (11):335-8. [Medline].

  13. Centers for Disease Control and Prevention. National notifiable diseases surveillance system (NNDSS). Case definitions. Available at http://wwwn.cdc.gov/nndss/script/casedefDefault.aspx. Accessed: August 3, 2015.

  14. Heinz FX, Stiasny K, Holzmann H, Grgic-Vitek M, Kriz B, Essl A, et al. Vaccination and tick-borne encephalitis, central Europe. Emerg Infect Dis. 2013 Jan. 19 (1):69-76. [Medline].

  15. Arrigo NC, Adams AP, Weaver SC. Evolutionary patterns of eastern equine encephalitis virus in North versus South America suggest ecological differences and taxonomic revision. J Virol. 2010 Jan. 84 (2):1014-25. [Medline].

  16. Kaiser R. Tick-borne encephalitis. Infect Dis Clin North Am. 2008 Sep. 22 (3):561-75, x. [Medline].

 
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Two ticks next to common match. On right is Ixodes scapularis, vector for Lyme disease. On left is Dermacentor tick (the larger one and the vector for Colorado tick fever).
 
 
 
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